1. Field of the Invention
The present invention relates to a valve for regulating the flow of a medium, of the type having a valve housing with an inlet for the medium that is to be regulated and an outlet for a regulated flow of the medium, a valve face with a valve opening, a movable sealing part which is arranged so that it is influenced by the flow of medium in the direction of opening of the valve, and that closes and opens the valve opening as well as regulates the flow of medium through the valve opening, and means for controlling the position of the sealing part.
2. Description of the Prior Art
A valve of this type is known from U.S. Pat. No. 5,265,594. Particularly in connection with the supply of gas to a patient connected to a breathing apparatus, it is very important that the amount of gas be controlled with great precision with the aid of such a valve. It is also very important that the sealing part, which here consists of a solenoid and a membrane, hermetically seals the valve opening when the supply of current to the solenoid is shut off. In connection with the valve specified in the aforementioned patent, this is ensured because the shaft of the solenoid, which influences the membrane and on which no magnetic force operates any longer when the current is shut off, is influenced by a relatively powerful spring so as to press the membrane against the valve face. During the regulation of the gas flow, a powerful spring of this sort can inhibit the motions of the solenoid. A relatively powerful solenoid can of course solve this problem, however, such a solenoid is relatively large, and is therefore space-consuming and has a high current consumption.